In order to compare sensitivity of EIA and RIA assay kits for hepatitis B and C virus (HBV and HCV, respectively) infection markers, 100 serum samples in total were collected form 50 adult women each in urban and rural areas in northeast China. The number of positive cases to the three infection markers on HBV (i.e., HBsAg +, anti HBs +, and anti HBc +) and the one on HCV (anti HCV +) were examined in two laboratories, i.e., in Laboratory A with EIA kits produced in China and in Laboratory B with RIA kits. HCV infection positivity (anti HCV +) was examined by EIA kits in both laboratories, but from different sources in and outside of China, respectively. The assay in Laboratory A gave 2 HBsAg + cases out of the 100 cases examined, whereas there were 9 positive cases in Laboratory B. In contrast, 19 cases were positive to anti HCV when examined in Laboratory A, and there were 3 cases in Laboratory B. Thus, the kits used in Laboratory A gave fewer HBsAg + and more anti HCV + cases than the kits used in Laboratory B. The prevalence of anti HBs + or anti HBc + and cases did not differ when assayed in the two laboratories with EIA and RIA kits, respectively. The agreement of positive and negative findings between the two sets of testing were 93%, 93%, 93%, 86% and 82% for HBsAg, anti HBs, anti HBc, HBV (i.e., either positive to anyone of the three markers or negative to all three markers), and anti HCV, respectively. The implication of the observation on epidemiology on HBV and HCV infection prevalence was discussed. In order to compare sensitivity of EIA and RIA assay kits for hepatitis B and C virus (HBV and HCV, respectively) infection markers, 100 serum samples in total were collected form 50 adult women each in urban and rural areas in northeast China. The number of positive cases to the three infection markers on HBV (ie, HBsAg +, anti HBs +, and anti HBc +) and the one on HCV (anti HCV +) were examined in two laboratories, ie, in Laboratory A with EIA kits produced in China and in Laboratory B with RIA kits. HCV infection positivity (anti HCV +) was examined by EIA kits in both laboratories, but from different sources in and outside of China, respectively. The assay in Laboratory A gave 2 HBsAg + cases out of the 100 cases examined, there were 9 positive cases in Laboratory B. In contrast, 19 cases were positive to anti HCV when examined in Laboratory A, and there were 3 cases in Laboratory B. Thus, the kits used in Laboratory A gave fewer HBsAg + and more anti H CV + cases than the kits used in Laboratory B. The prevalence of anti HBs + or anti HBc + and cases did not differ when assayed in the two laboratories with EIA and RIA kits, respectively. The agreement of positive and negative findings between the two sets of testing were 93%, 93%, 93%, 86% and 82% for HBsAg, anti HBs, anti HBc, HBV (ie, either positive to anyone of the three markers or negative to all three markers), and anti HCV , respectively. The implication of the observation on epidemiology on HBV and HCV infection prevalence was discussed.